1. Field of the Invention
This invention uses a novel technique to make electrical heating elements which may be used up to 900.degree. C. This technique also provides new methods for manufacturing ceramic composites, which may be used as both electrical heating elements and oxidation resistant materials.
2. Description of the Prior Art
Generally, heating elements are made from metals like Mo and W, and alloys like Fe-Cr-Al and Ni-Cr, SiC and metal silicides. The alloy heating element is produced by melting in the electric induction or arc furnaces (sometimes alloys have to be melted several times to achieve homogeneity) and then is pressed or extruded. Silicon carbide and molybdenum disilicide heating elements are made by powder metallurgy and have to be sintered at high temperatures and extended times in H.sub.2 and CO atmospheres. In the powder metallurgy industry, sintering is often the most costly step of the total manufacturing process, especially when high temperature sintering is involved. Melting and casting are also costly. In addition, because the manufacture of conventional materials is limited by processing, heating elements can be produced only within a predetermined resistivity range.
It is evident that the prior art methods exhibit serious disadvantages, and it is a primary object of the present invention to obviate these by providing a micropyretic synthesis method and composition for production of electrical heating elements and oxidation resistant materials.